THRIFT-523. Make ax_lib_event.m4 work with newer versions of libevent

libevent changed is minor version numbering scheme with version 1.4.0,
and the simplistic comparison function used by ax_lib_event.m4 did not
work with the new scheme.  This patch introduced a more accurate
comparison function that works with all existing versions of libevent.

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@799016 13f79535-47bb-0310-9956-ffa450edef68
1 file changed